Driving safety is the most important matter for drivers, and tires play a significant role in driving safety. The tire of a wheel should have an appropriate pressure. Too high a tire pressure or too low a tire pressure affects driving safety. However, the driver cannot learn the tire pressure from the appearance thereof but can only rely on the equipment and personnel of a vehicle repair shop. Needless to say, the driver cannot monitor the tire pressure in a running vehicle. Therefore, the related manufacturers have developed various tire pressure detectors to monitor the tire pressure.
A R.O.C. patent No. M315663 disclosed a “Detective Air Tap Cap Assembly”, which comprises a casing, a cap, a power supply device, and a detective circuit board. The cap is embedded in on side of the casing, and the detective circuit board is press-fitted to the interior of the casing. The cap has batteries supplying power to the detective circuit board. The detective air tap is fastened to the air tap of a tire, and the air in the tire enters the casing via an air inlet. The detective circuit board detects the status of the tire. A control unit analyzes the information and wirelessly transmits the signals to a receiving device. Then, the driver learns the status of the tire from the receiving device. However, the prior-art patent does not have an air chamber but uses a valve core needle to press against the valve core of the air tap to control the air flowing from the tire to the tire pressure detection device. Such a means may result in air leakage. On the other hand, the cap, which is embedded in the casing, uses a washer to prevent from the air leakage of the tire pressure detection device. However, such an approach has only a limited effect on preventing from the air leakage in the engagement region of the cap and the casing. As the prior-art patent does not have an air chamber, there is usually difference between the detection result and the actual status. Thus, the driver may receive wrong information, and driving safety may be affected. Further, the batteries are installed inside the cap. However, the cap is embedded in the casing and unlikely to be dismantled from the casing. Thus, the exhausted batteries cannot be replaced. In other words, the entire service life of the detection device is equal to the service life of the batteries. For consumers, such a limited service life means a poor economic efficiency.
In the prior-art tire pressure detection device, airtightness is inferior, batteries are hard to replace, economic efficiency is low, detection results are apt to be inaccurate, and air leakage is likely to occur after a long time use.